Tuning control mechanism



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W. M. HURST TUNING CONTROL lMECHANISM Eiled April 3. 1947 FIG.|

FIG.4

Angular Displacameni INVENTR., WILLI AM HURST FIG.5

ATTORNEY Patented Dec. 28, i948 TUNING CNTROL MECHANISM William M. Hurst, Douglaaton, N. Y., assignor to Hazeltine Research, Ine.,

poration oi Illinois Chicago, lli., a cory Application April 3, 1947, Seria] No. 739.207

2 Claims. i

This invention is directed to control mechanisms. Although the invention is suited for various applications, it is particularly useful for controlling the variable element of an adjustably tuned circuit and hence will be described in that environment. l

Control mechanisms of many types are presently employed in connection with adjustably tuned electrical circuits for the purpose of adjusting the circuit to resonate at any selected one of a plurality of predetermined frequencies within a given operating frequency range. These mechanisms are ordinarily associated with the rotor of an air-dielectric condenser or with the adjustable core of a variable inductance element.

Push-button tuning devices represent one well? known type of control mechanism, which are employed for such purposes. Prior control mechanisms comprise more or less complicated mechanical or mechanical and electric arrangements which are rather expensive to manufacture. Also. these prior control mechanisms are often bulky and hence objectionable for some purposes such as for airborne or portablelnstallations wherein size and weight considerations sometimes predominate. Also, accuracy of the frequency settings of some control mechanisms heretofore em- `ployed has not been particularly exact for frequencies in the ultra-hlgh-frequency portion of the frequency spectrum. Consequently, efforts to reduce the size and complexities of such arrangements have usually resulted in the sacrificing of accuracy.

It is an object of the invention, therefore, to provide a new and improved tuning control mechanism which is not subject to one or more of the above-mentioned disadvantages and limitations of prior such mechanisms'.

It is another object of the invention to provide a simple, compact, relatively inexpensive, yet reliable tuning control mechanism.

It is a further object of the-invention to provide a small tuning control mechanism which reportions and a shaft rotatably supported by the first means. The mechanism also includes a crank, connected to the shaft for rotation with respect to the first means and having a stop portion at the free end thereof for selectively regislitiv (Ci. 'I4-10.41)

tering with individual ones of the stop portions. for establishing predetermined angular relationships between the first means and the crank. A follower is pivotally connected to the crank for actuation thereby and has a first portion movable with reference to any selected one of the registering stop portions for positioning a, controlled element in= accordance with the-relative positions of the first means, the crank, and the follower. The vfollowerhas a second portion remote from the stop portion of the crank and the axis of the shaft. The control mechanism further includes a plurality of radially disposed adjusting screws on the first meansfor selective engagement with the second portion of the follower for adjusting the follower about the pivotal connection therefor with reference to any selected one of the registering stop portions, thereby to permit for each of the predetermined angular relationships between the first means and the crankan adjustment of the position of the controlled element which is independent `of the corresponding predetermined angular relationship between the first means and the crank. The control mechanism includes means connected to the crank and the follower for biasing the second portion of the follower into engagement with individual ones of the adjusting screws and also includes a locking means on the first means for maintaining each of the adjusting screws in a selected position of adjustment.

For a better understanding of the present in vention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawing, Fig. 1 is a rear elevational view of a tuning control mechanism in accordance with the invention; Fig. 2 is a. sectional view on the line 2 2 illustrating also the connection to a device controlled thereby; Fig. 3 is an elevational view of a portion of the arrangement of Fig. 1 showing a linkage connection secured thereto; Fig. 4 is a simplified representation of the arrangement of Fig. l illustrating,r two positions of .adjustment thereof; and Fig. 5 represents the tuning curve of an electrical device which is associated with the control mechanism of Fig. l.

Referring now to Fig. 1 of the drawing, the tuning control mechanism in accordance with the present invention comprises a first means or disc Il) constructed of a suitable material such as me tal or plastic and including a plurality of radially disposed stop portions il, ii on the rear vface thereof. These stop portions may bein the form of tapered notches which are preferably equally spaced near the periphery of the disc I0. The disc i0 also includes a pair of elongated apertures 20, 2li which are adapted to receive screws for attaching the disc to a control panel or to the chassis of an electrical apparatus (not shown). The control mechanism also includes a second means in the form of a crank I2 of spring material such as steel, one end of which has a suitable bore therein which is attached by way of a press fit to a shaft I3 (see also Fig. 2. The shaft I 3 is rotatably supported in a bore I4 in the disc I3 and carries at the end which projects beyond the front surface I5 of the disc a control knob I9 forrotating the shaft. The crank I2 is therefore rotatable relative to the disc III and is provided with a stop portion I l at the free end thereof, preferably in the form of a rounded head on a pin i9 which passes through an aperture in the crank as illustrated in Fig'. 2 of the drawing. stop portion i8 is adapted selectively to cooperate with individual ones of the radially disposed stop portions II. ll on the disc I0, for establishing predetermined relative positions, specifically predetermined angular relationships between the disc I0 and the crank I2, as will be explained subsequently.

The control mechanism also includes a third means in the form of .a follower 2| which is pivotally connected by the shank portion of the pin |9 to the crank I2 for actuation thereby. The follower 2| is a plate having the approximate shape of a parallelogram and is preferably disposed between the crank i2 and the flat surface 55 on a cylindrical shoulder 23 (see Fig. 2) which acts as bearing surface for the follower. The latter is provided with an elongated aperture 24 through which the shaft |3 extends in order to engage the crank I2. The follower 2i has a portion 29 which is remote from the pivot comprising the pin i9 and which is movable with respect to any selected one of the co-operating stop portions II, I3 for positioning a controlled element, presently to be described, in accordance with the relative positions of the disc i0. the crank i2. and the follower 2 I.

The remote portion 25 of the follower 2| includes a pivot pin 29 which is connected to the movable element or rotor (not shown) of a con denser 30 which, in combination with a conventional winding (not shown), may comprise the tunable portion of an electrical circuit. The rotor of the condenser 30 is attached to a shaft 3| which is coaxial with the shaft I3 of the control mechanism. Shaft 3| is mechanicallycoupled to theceive the pins 29 and 33. The pins are maintained in their positions in the notches by means of a coil spring 31 having the looped ends thereof snapped over the pins.

The follower 2| also includes a second portion 4ll`isee Fig. l) which is remote from the stop portion i3 of the crank I2 and the axis of the shaft i3, This portion is at one of the corners of the parallelogram and carries a. hardened steel roller 4| which is rotatably mounted on the undersurface of the follower by a pin 42. 'I'he roller 4i projects into an annular recess 44 on the rear portion of the disc III.

The control mechanism in accordance with the invention also comprises a plurality of adjusting screws 45, which are radially disposed in the disc i0 adjacent the stop portions Il, ii. These screws extend from near the periphery of the disc Ill into the annular recess 44 for the purpose of adjusting the position of the movable A .4 portion 23 of the follower 2l with respect tol any selected oneof the co-operating stop portions, thereby to permit for each of the predetermined angular vrelationships of the crank I2 with respect to the disc I0 an adjustment of the position of the rotor of the condenser 30 which is independent of the corresponding predetermined relative position for the disc and the crank. These screws preferably have hardened ends 45 to prevent cold working or deformation 'by the action of the roller 4I which is biased into engagement with individual ones of the pins by means of an arcuate spring 41 that is restrained with its ends lodged between a lug 45 on the crank I2 and the head of the pin 42. Locking screws 49, 49 are mounted in suitable bores near the front surface I5 of the disc lII for engaging and maintaining each of the adjusting screws 45 in a selected position of adjustment. a

Considering now the operation of the described control mechanism. rotation of the control knob il through an angle produces a corresponding angular movement of the shaft i3 and the crank I2 which is secured thereto. This angular movement of the crank I2A causes the stop portion i3 thereon comprising the rounded head of pin I9 alternately to snap into and to ride out of the successive stop portions II. ii on the disc I0 because of the resilient nature of the crank. The crank I2 drives the follower 2| in the same direction that it moves through the pivot pin I9. The roller 4| on the follower 2i, which is biased in a direction away from the shaft I3 by the spring 41, is maintained by the spring in engagement with the ends 49, 48 of the successive screws 45. 45 so that the pin 29 on the remote portion 25 of the follower 2l moves in an arcuate path about the shaft I3. Neglecting for the moyment the accurate adjusting feature provided by the screws 45, 45, the pin 29 acting through the link'34. the pin 33, the crank 32, and the shaft 3| turns the rotor of the condenser 39 by an amount corresponding effectively to the rotation imparted to the shaft i 3 by the control knob I6. thereby adjusting the tunable circuit including the condenser 30 a given amount. The turning of the knob i6 is discontinued when the stop portion I8 engages the selected one of the radial stop portions Il. Rotation of the knob i6 so that the stop portion I8 rests in a different stop'portion` ment. The locking screw 49 vis then tightened.

When a screw 45 is adjusted outwardly, as shown for position A in Fig. 4, the roller 4I rests against the end 46 of the screw so that the follower 2i assumes the position shown in broken-line construction with the pin 29 disposed at position A'. When the screw 45 is adjusted inwardly with respect to the periphery of the disc i0 to the position B illustrated in Fig. 4, the follower 2i is displaced by the action of the adjusting screw 45 on the roller 4| so that the follower rests in the posi tion shown in dash-dot line construction with the pin 29 at the position Bf It will be manifest from the illustration that the elongated aperture 24 in any one of the predetermined positions therefor.

, While the adjustment has been described in connection with a single stop for the crank I2, it will be manifest that a similar adjustment may be made by manipulating the proper adjusting screw 45 at any other of the (zo-operating stops.

Curve C of Fig. 5 represents the frequencyangular displacement characteristicl of an adjustably tuned electrical device which may be associated with the control mechanism of the instant invention. It will be observed that this curve varies considerably from linearity. In spite of this nonlinear tuning characteristic, the wide range of adjustment afforded at individual stop positions on the instant control mechanism permits the use of this mechanism with such an electrical device. Also, the uniform spacing between individual position stops presents no drawback in spite of the nonlinearity of such a tuning curve. The instant stop mechanism may, therefore, be employed in conjunction with a scale having uniformly spaced graduations thereon for indicating the position of the controlled' element at each of a plurality of positions of adjustment thereof.

With the instant arrangement, the force required to operate the control knob I6 in a clockwise direction is'substantially the same as that required to turn the knob in a counterclockwise direction, thus imparting a uniform feel" to the control knob.

While a control mechanism has been described in connection with stop portions i Lil which are equally spaced, it will be clear that for some ap- 6 connected to said crank for actuation thereby and having a first portion movable with reference to any selected one of said registering stop portions for positioning a controlled element in accordance with the relative positions of said first means, said crank'and said follower; said foilower having a second portion remote from said stop portion of said crank andthe axis of said shaft; a plurality of radially disposed adjusting screws on said first means for selective engagement with said second portion of said follower for adjusting said follower about the pivotal connection therefor with reference to any selected one of said registering stop portions, thereby to permit for each of' said predetermined angular relationships between said first means and said crank an adjustment of the position of said controlled element which is independent of the corresponding predetermined angular relationship between said first means and said crank; means connected to said crank and said follower for biasing said second portion of said follower into engagement with individual ones of said adjusting screws; and locking means on said first means for maintaining each of said adjusting screws in a` selected position of adjustment.

2. A tuning control mechanism comprising: a

n first means including a pluralityA of radially displications these `stop portions may have anunmechanical arrangements if desired. It will also be clear that mechanisms other than tunable electrical devices may be controlled by the cony trol mechanism of the present invention.

From the foregoing description, it will be manifest that a control mechanism in accordance with the present invention is compact, relatively inexpensive, reliable, and capable of a wide range of adjustment.

While there has been described what is at present considered to be the preferred embodiment of this invention, it will be obvious-to those skilled in the art that various changes and modiflcations may be made therein without departing from the invention, and itis, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What isclaimed is:

1. A tuning control mechanism comprising: a first means including a plurality of radially disposed spaced stop portions; a shaft rotatably su-pported by said first means; a crank, connected to said shaft for rotation -with respect to said first means and havinga stop portion at the free end thereof for selectively registering with individual ones of said stop portions, for establishing predetermined angular relationships between said rst means and said crank; a follower pivotally thereby to permit for each of said predetermined a spring connected to said crank and said folposed spaced stop portions; a shaft rotatably supported by said first means; a crank, connected to said shaft for rotation with respect to said first means and having a stop portion at the free end thereof for selectively registering with individual ones of said stop portions, for establishing predetermined angular relationships between said iirst means and said crank; a follower pivotally connected to said crank for actuation thereby and having a first portion remote from said stop portion of said crank and movable with reference to any selected one of said registering stop portions for positioning a controlled element in accordance with the relative positions of said first means, said crank` and said follower; said follower having va second portion remote from said stop portion of said crank and the axis of said shaft; a plurality of radially disposed adjusting screws adjacent said stop portions on said first means for selective engagement with said second portion for adjusting said follower about the pivotal connection therefor with reference to any selected one of said registering stop portions,

angular relationships between said first means and said crank an adjustment of the position of said controlled element which is independent of the corresponding predetermined angular relationship between said first means and said crank;

lower for'bias'ing said second portion of said follower into engagement with individual ones of said adjusting screws; and locking means on said first means for maintaining each of said adjusting screws in a selected position of adjustment. WILLIAM M. HURST.

REFERENCES CITED The following references are of file of this patent:

UNITED STATES PATENTS record in the 

